Many types of ballasts for powering gas discharge lamps have metallic housings in which the cover is riveted to the base. Such housings provide durable mechanical protection of ballast electrical components, but have several disadvantages. For instance, metallic housings are relatively heavy, require riveting machinery for attaching the cover to the base, and are generally not reusable if opened for inspection or repair of the ballast circuitry.
Some other types of ballasts have a housing that may be non-destructively disassembled to allow repair, etc. An example of such a housing is described in U.S. Pat. No. 5,691,878. Such housings are typically composed of plastic, are lighter in weight than metallic housings, and may be manually assembled and disassembled. However, such housings may not provide an adequate degree of heat-sinking to maintain an appropriate operating temperature for the ballast electrical components, which is critical to providing a reliable ballast with an acceptable operating life.
A shortcoming that is common to existing ballasts pertains to the problem of providing input and output wires. It is well known in the ballast industry that many customers require that the ballast manufacturer provide ballasts with pre-installed input and output wires. To meet this requirement, existing ballasts employ either: (i) a hard-wired scheme in which the wires are actually soldered to the circuit board; or (ii) wire-trap connectors that are soldered to the circuit board. In the former case, the wires are usually manually soldered to the circuit board in a separate process after the circuit board has been populated with components and initially soldered. The requirement of a separate soldering process renders such ballasts ill-suited for production in an automated manufacturing environment. Ballasts that employ input and output connectors that are soldered to the circuit board along with the other electrical components avoid the need for a separate soldering operation. However, since the wires cannot be managed during the soldering operation, they must be inserted manually on a post-production basis (i.e., after the ballast is completely assembled). This approach has obvious logistical and efficiency problems. For example, product shipping is inevitably delayed while the wires are being inserted into the input and output connectors.
What is needed therefore is a housing that provides secure and reliable mechanical protection of electronic ballast circuitry, that is readily assembled and nondestructively disassembled, that provides adequate heatsinking for electrical components, and that accommodates efficient installation of wires in an automated manufacturing environment. Such a ballast housing would represent a significant advance over the prior art.